<div id="map"></div>

<script>
    var map = new mapboxgl.Map({
        container: 'map',
        style: 'mapbox://styles/mapbox/streets-v9',
        zoom: 1
    });

    map.on('load', function() {
        // Add GeoJSON data
        map.addSource('source', {
            'type': 'geojson',
            'data': {
                'type': 'Feature',
                'properties': {},
                'geometry': {
                    'type': 'Polygon',
                    'coordinates': [
                        [
                            [-30, -25],
                            [-30, 35],
                            [30, 35],
                            [30, -25],
                            [-30, -25]
                        ]
                    ]
                }
            }
        });

        // Load an image to use as the pattern
        map.loadImage(
            'https://upload.wikimedia.org/wikipedia/commons/thumb/6/60/Cat_silhouette.svg/64px-Cat_silhouette.svg.png',
            function(err, image) {
                // Throw an error if something went wrong
                if (err) throw err;

                // Declare the image
                map.addImage('pattern', image);

                // Use it
                map.addLayer({
                    'id': 'pattern-layer',
                    'type': 'fill',
                    'source': 'source',
                    'paint': {
                        'fill-pattern': 'pattern'
                    }
                });
            }
        );
    });
</script>
